The number of unpaired electrons in 1s² 2s² 2p³ is -

1. 2

2. 0

3. 3

4. 1

The quantum numbers of four electrons are given below.

                                  n            $\mathcal{l}$           m          s 

(1) Electron 1             3            0             0           -1/2

(2) Electron 2             4            0             1           1/2

(3) Electron 3            3             2             0           1/2

(4) Electron 4            3             1             0           -1/2

The correct order of decreasing energy of these electrons is - 

(A) Electron 3 > Electron 1 > Electron 4> Electron 2

(B) Electron 4> Electron 2 > Electron 3 > Electron 1

(C) Electron 3 > Electron 2 > Electron 4 > Electron 1

(D) Electron 2 > Electron 4 > Electron 3 > Electron 1

The maximum number of atomic orbitals associated with a principal quantum number 5 is

(A)9

(B)12

(C) 16

(D) 25

Rutherford's scattering experiment is related to - 

(A) Nucleus

(B) proton

(C) Electron

(D) Neutron

The total number of neutrons in dipositive zinc ions with mass number 70 is -

(A) 34

(B) 40

(C)36

(D) 38

When accelerated electrons are direct against an anticathode in an X-ray tube, the radiation obtained has a continuous spectrum with a wavelength minimum,

$\lambda$_min = (1.24 x 10^-6/V) m, where V is the voltage used for accelerating the electrons. Calculate $\lambda$_min for V= 5 x 10⁴ volts.

(A) 1.25 Å

(B) 0.75 Å

(C)0.25 Å

(D) 1.00 Å

The wavelengths of two photons are 2000 Å and 4000 Å respectively. What is the ratio of their energies?

(1) 1/4

(2) 4

(3) 1/2

(4) 2

The ion that is isoelectronic with CO is-

(A) CN^-

(B) O₂⁺

(C) O₂^-

(D) N₂⁺

When the atoms of gold sheet are bombarded with a beam of $\alpha$ -particles, only a few a-particles get deflected where as most of them go straight undeflected. This is because

(A) The force of attraction on the $\alpha$-particles by the oppositely charged electron is not sufficient

(B) The nucleus occupies much smaller volume as compared to the volume of atom

(C) The force of repulsion on fast moving $\alpha$-particles is very small.

(D) The neutrons in the nucleus do not have any effect on $\alpha$-particles

The brackett series of spectral lines arise when an electron in an excited hydrogen atom jumps from an energy level

(1) n=5 to n=1

(2) n=5 to n=3

(3) n=5 to n=4

(4) n=5 to n=2